The objective of this improvement project is to provide adequate caging, housing, maintenance, and an enriched environment to chimpanzees infected with the Human Immunodeficiency Virus (HIV) that are on protocols supported through federally funded projects. The individual huts at SFBR were originally designed to house primates on shortterm projects. However, HIV infected chimpanzees require long-term housing and monitoring. It is therefore necessary to upgrade the existing facilities to provide adequate cage space for the long-term holding of large chimpanzees. It is imperative to provide housing that complies with guidelines and regulations and, additionally, to provide an environment that will enrich the psychological well being of the animals. The specific aims of this project are to renovate eight isolation huts to accommodate four large (35 sq. ft.) pens; improve the lighting, ventilation, and temperature regulation in these eight huts; upgrade the heating and ventilation systems in six indoor- outdoor huts for long-term housing; purchase six large (30 sq. ft.) chimpanzee cages with squeeze backs for short-term housing; and provide environmental enrichment for all long-term holding facilities to improve the psychological well being of HIV infected animals. The proposed improvements will facilitate adequate long-term maintenance and improve the well being of an increasing number of HIV-infected adult chimpanzees.